Conventionally, in a vehicle such as an automobile and a motorcycle, for example, in the case of an engine in which fuel injection and ignition are controlled by an electronic controller, an idling speed control valve (ISCV) which is another electronically controlled air control valve is provided on a side of a throttle valve as an air control valve. The ISCV controls idle-up and stabilize idling when an air condition is operated. Specifically, for example, the ISCV controls an intake air amount to the engine and controls the engine to keep a target rotation speed during idling when a vehicle is in an idling state by tightening the throttle valve.
The ISCV, for example, includes a stepping motor, a rotating shaft of the stepping motor, and a valve body. The stepping motor works as an actuator which actuates a valve. The valve body includes a screw mechanism between the shaft and moves in an axial direction of the shaft. A top side of the shaft is set to a male screw, a nut provided to the valve is screwed to the male screw, and based on normal/reverse rotations of the shaft, a flow rate of intake air to an engine during idling is controlled when the valve body is moved to an axial direction of the shaft.
A flow rate control valve described in Patent Literature 1 is known as an example of the above-described flow rate control valve. The flow rate control valve is closed by closing both of a discharge port and a suction port by a valve body.